Sentaurus Device Electromagnetic Wave Solver
1. Getting Started

1.1 Overview
1.2 Starting EMW
1.3 Input and Output File Types
1.4 Accessing Help on Syntax

Objectives

• To learn how to start EMW.
• To explain which file types are used in EMW simulations.
• To demonstrate how to access help on syntax.

1.1 Overview

Sentaurus Device Electromagnetic Wave Solver (EMW) is an electromagnetic solver based on the finite-difference time-domain (FDTD) method. It can numerically solve the temporal evolution of electromagnetic waves in a device structure defined on a tensor grid. The main result is the absorbed photon density distribution, which is typically used in subsequent electrical simulations.

1.2 Starting EMW

The binary emw offers three different FDTD kernels:

Command	FDTD kernel	Notes
emw or emw -plus	Default kernel	Actively developed kernel
emw -acceleware	Interface to Acceleware hardware-accelerated kernel	Available only if a hardware acceleration card and license from Acceleware have been purchased
emw -old	Old emlab kernel	Obsolete, no longer developed, and only available for backward compatibility

Most often and throughout this module, the default kernel of EMW is used.

To start EMW from the command line, use:

> emw [command_file_name]

where the optional command_file_name is a valid command file of EMW, for example:

> emw pp1_eml.cmd

To list the command-line options, use:

> emw -h

To list all of the installed EMW releases, use:

> emw -releases

To check the default version number, use:

> emw -v

To run a particular release version, use:

> emw -rel F-2011.09-SP1

1.3 Input and Output File Types

The main input and output file types used in EMW simulations are shown in Figure 1. The file names can be specified in the EMW command file (for details, see Section 2.2 Command File).

Figure 1. Overview of input and output files for EMW. (Click image for full-size view.)

1.3.1 Command File (*_eml.cmd)

The command file is the main input file for EMW. It contains all the model settings and file specifications, and can be edited. This file is referred to as the command file or input file.

1.3.2 Tensor-Grid File (*_msh.tdr)

EMW needs a tensor grid to run FDTD simulations. A typical example of a tensor grid is shown in Figure 2. How to generate a suitable tensor-grid file with Sentaurus Mesh is described in the Sentaurus Mesh module, Section 3. Using Tensor-Product Mesh Generator.

Figure 2. Example of a tensor grid of a CMOS image sensor; oxide removed for visualization. (Click image for full-size view.)

1.3.3 Parameter File (*_eml.par)

EMW allows you to define the optical parameters as a complex refractive index (CRI) in the material parameter file. It uses the same CRI library as Sentaurus Device. Therefore, the same parameter file as for Sentaurus Device can be used (refer to the Sentaurus Device module, Section 1.3 Parameter File and Section 5.2 Model Parameter Definitions for Nonsilicon Material).

The optical parameters then are read from the corresponding ComplexRefractiveIndex section, for example:

Material = "Silicon" {   
  ComplexRefractiveIndex {
  Formula = 1
  NumericalTable (
    * WAVELEN(um)	n	k
    0.250	1.694	3.6606E+00;
    0.260	1.800	4.0760E+00;
    ...
  )
}

1.3.4 Plot, Sensor, and Extractor Files (*_eml.tdr)

As multiple Plot sections are allowed, the plot file names are defined in the corresponding Plot sections.

1.3.5 Inspect File (*_eml.plt)

An Inspect file is used when global values have to be stored, such as the integrated absorbed photon density in a certain volume or the photon flux through a surface. The results can be viewed using Inspect or Tecplot SV (see the Inspect module or Tecplot SV module).

1.3.6 Log Files (*_eml.log, *_eml.out)

EMW generates the log file during a simulation run. It contains information about input parameters, and the models and values of physical parameters used in the simulation. The log file contains more details than the information written to the standard output (.out) during the simulation.

1.4 Accessing Help on Syntax

Help for the syntax of each keyword can be obtained using the EMW binary with the -P command-line option. For example, to view all of the allowed options for the keyword Quantity in the Plot section, in a shell, type in a shell prompt:

> emw -P:plot:quantity
************************************************************************
***                     Sentaurus Device EMW                         ***
...
Quantity = { <identifier>, ... }  
  Default value: { AbsElectricField }
  Exclusive options are: AbsElectricDisplacement
                         AbsElectricField
...